Growth Hormone Disorders
Definition | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Management
Definition
Growth hormone disorders refer to conditions resulting from either excess or deficiency of growth hormone (GH), impacting growth, metabolism, and overall endocrine function.
Aetiology
- Growth hormone deficiency (GHD): congenital (genetic mutations, structural pituitary abnormalities) or acquired (tumours, radiation, trauma, infection).
- Growth hormone excess: most commonly caused by a pituitary adenoma leading to acromegaly in adults and gigantism in children.
- Laron syndrome: GH receptor defect leading to resistance and short stature.
Pathophysiology
- GH is secreted by the anterior pituitary under regulation of GHRH (stimulatory) and somatostatin (inhibitory) from the hypothalamus.
- GH stimulates IGF-1 production in the liver, promoting bone growth, protein synthesis, and metabolic regulation.
- Deficiency results in impaired growth and metabolic dysfunction, while excess leads to tissue overgrowth and metabolic disturbances.
Risk Factors
- Family history of GH disorders.
- Genetic mutations affecting GH secretion or action.
- Pituitary tumours or hypothalamic dysfunction.
- Head trauma, radiation therapy, or CNS infections.
- Chronic systemic illness or malnutrition.
Signs and Symptoms
- GH deficiency:
- Short stature or growth retardation in children.
- Increased fat mass, reduced muscle mass.
- Hypoglycaemia, fatigue, and decreased bone density.
- GH excess:
- Gigantism in children (excessive height, enlarged extremities).
- Acromegaly in adults (coarse facial features, enlarged hands/feet, joint pain).
- Metabolic effects including insulin resistance, hypertension.
Investigations
- Serum IGF-1 levels: marker of GH activity.
- GH stimulation test: used for suspected GH deficiency (insufficient GH rise after stimulation).
- Oral glucose tolerance test (OGTT): failure to suppress GH post-glucose load suggests acromegaly.
- Pituitary MRI: to detect pituitary adenomas.
Management
Note: The following information is for awareness only, as management is carried out by a specialist/MDT.1. GH Deficiency:
- Recombinant GH therapy: daily subcutaneous injections.
- Monitoring: regular assessment of growth velocity and metabolic parameters.
2. GH Excess:
- Transsphenoidal surgery: first-line treatment for pituitary adenomas.
- Medical therapy: somatostatin analogues (e.g., octreotide), GH receptor antagonists (e.g., pegvisomant).
- Radiotherapy: used for resistant cases.